1. Field of the Invention.
The present invention generally relates to a multi-speed hub for the driven wheels of bicycles and similar vehicles. Such a multi-speed drive hub can generally have a hub axle which can be non-rotationally attached to a bicycle frame, a driver device rotationally mounted on the hub axle, a hub sleeve which can be concentric to the hub axle and mounted on the driver, and a hub shift transmission acting between the drive and the hub sleeve. For providing the multiple gear ratios of the hub, the hub shift transmission can have first and second planetary gear sets, each having at least one stage. To provide the first and second planetary gearsets, there can preferably be a first planetary carrier mounted rotationally on the hub axle, with first and second multi-stage planet wheels mounted rotationally on the first planetary carrier. There can also be corresponding sets of first and second sun wheels, corresponding to, and being engaged with each of the individual stages of the first and second multi-stage planet wheels. The first and second sun wheels are rotationally mounted on the hub axle, and can be optionally non-rotationally connected to the hub axle in any respective axial connection position by means of corresponding freewheels.
In addition, there can be a first ring gear engaged with one of the stages of the first multi-stage planet wheel, and a second ring gear engaged with one of the stages of the second planet wheel, wherein the ring gears provide the output from the planetary gearsets.
2. Background Information
A hub with the capability of generating a number of speeds by means of two planetary gear sets located next to one another is disclosed in German Patent Application No. 41 42 867, which corresponds to U.S. Pat. No. 5,273,500. In this hub, a ring gear of a first planetary gear set is actively connected via a coupling system, acting in one direction of rotation, to the hub sleeve. The gear ratio achieved in a second planetary gear set is transferred to the first planetary gear set via an output, or driven second planetary carrier, and is superimposed on the gear ratio of the first planetary gear set. The system of the first and second planetary gear sets, in this sense, can essentially be considered to be a transmission with a gear reducer unit. Such an arrangement, however, does not provide the maximum number of gear ratios per number of available gear stages of the planetary gears.